On May 29, 2010, at 9:58 PM, Garrett Cooper wrote:
So basically you're saying deal with an LRU snapshot deletion when you reach a certain threshold of free space, type scheme? This might get tricky, but it does lend itself to other systems I suppose (I hate to mention it, but the best one I can think of is Windows' system restore... there might be something else available with OSX's Time Machine).
Time Machine works almost exactly that way. It stores as far back in history as you have hard drive space to hold it.
What would be more tricky is when the automated system is filling in a bunch of useless snapshots unnecessarily, but as you'd be providing the snapshot criteria, I suppose that you would know what snapshots you want to save and what ones you want to toss...
I don't think add any trickery. The snapshots are again analogous to how Time Machine works, where you have hourly snapshots, then a week's worth of daily, then a month's worth of weeklies, then as many monthly snapshots as will fit on your hard drive. If you run out of space, delete November, then December.
It's an interesting thought though -- just increases the overall complexity of the system and may only meet one need.
I think the additional complexity would amount to adding a config option to the code that gets run when a disk is full that executes an arbitrary command, namely a user-space shell script that deletes the oldest automatically-generated snapshot.
The "only one need" that it addresses is that now FreeBSD would come with a built-in recovery system. Did a "make installworld" but screwed something up and ended up with a non-bootable system? Pop in a recovery CD and revert to the "4 hours ago" snapshot, then reboot. Voila! It never happened. Accidentally deleted /etc/passwd? Retrieve the version from /.zfs/snapshot/weekly-2010-21/etc/passwd . Just realized that you deleted an important file 3 months ago and only keep 2 weeks worth of backups? No problem, as long as you haven't filled up your hard drive since then.
-- Kirk Strauser _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
